This invention relates to aircraft interior equipment, and more particularly, to aircraft ejection seats.
When a pilot or other aircraft occupant ejects from an aircraft moving at high speed, his or her body is subjected to various acceleration and aerodynamic conditions that if not properly controlled may lead to injury. One area of particular concern is the crewmember's head and neck. During the initial acceleration of the ejection seat, acceleration forces acting on the crewmember's head and helmet tend to pitch the crewmember's head forward and down. This effect is especially pronounced if the helmet is equipped with night vision and/or heads-up-display equipment mounted forward of the crewmember's face. Next, aerodynamic flow over the top of the helmet causes a large pressure drop to occur so that the normal pressure inside the helmet acts to pull the helmet upward, jerking the crewmember's head up and back from its previous tilted-forward position. After the seat has cleared the aircraft, aerodynamic forces acting on the helmet and ejection seat may interact to cause the crewmember's head to slam back against the headrest and/or flail in the windblast.
U.S. Pat. No. 3,645,259 to Schulman discloses an inflatable airbag positioned beneath the pilot's chin that inflates during ejection. This approach addresses the problem of the crewmember's head tilting forward upon initial acceleration but does not address the aerodynamic lift and flailing problems associated with high-speed ejection. U.S. Pat. No. 4,899,961 to Herndon discloses a headrest having inflatable lateral restraints. This approach addresses the problem of the crewmember's head flailing in the windblast but does not address the tilt-forward or aerodynamic lift issues. U.S. Pat. No. 4,436,262 to Cummings discloses a wind blast head protector in the form of a canopy that deploys over the top of the crewmember's helmet. This approach addresses the problem of the crewmember's helmet lifting off the crewmember's head and purports to address the issue of head flailing in the wind blast, but does not address the problem of the crewmember's head tilting forward and jerking back as acceleration forces give way to wind blast forces and may impede the crewmember's separation from the seat when the crewmember's parachute deploys.